Issue 6737 - Use String.includes instead of String.indexOf

lib/downloader.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 189 matching lines @@
    * Generates the real download URL for an object by appending various
    * parameters.
    * @param {Downloadable} downloadable
    * @return {string}
    */
   getDownloadUrl(downloadable)
   {
     const {addonName, addonVersion, application, applicationVersion,
            platform, platformVersion} = require("info");
     let url = downloadable.redirectURL || downloadable.url;
-    if (url.indexOf("?") >= 0)
+    if (url.includes("?"))
       url += "&";
     else
       url += "?";
     // We limit the download count to 4+ to keep the request anonymized
     let {downloadCount} = downloadable;
     if (downloadCount > 4)
       downloadCount = "4+";
     url += "addonName=" + encodeURIComponent(addonName) +
         "&addonVersion=" + encodeURIComponent(addonVersion) +
         "&application=" + encodeURIComponent(application) +
@@ skipping 192 matching lines @@
    * @type {number}
    */
   hardExpiration: 0,
 
   /**
    * Number indicating how often the object was downloaded.
    * @type {number}
    */
   downloadCount: 0
 };